This invention relates to packages made from flexible film material, and more particularly, to packages made from such material and having an opening sealed by a novel non-resealable (by hand) "peelable" seal. In general, this invention relates to bag-like packages of kinds suitable for coffee or other products which require gas or moisture protection, but which permit ready access to their contents through an opening having a peelable seal.
Certain products, such as coffee, have heretofore been marketed in flexible packages, so-called "soft packs". One such package consists of a bag constructed from a laminated film material of three or four plies, which provides physical containment for the product as well as a moisture and gas barrier. Various film materials have been used, but typically they include one or more plies of materials which provide a desired physical strength and dimensional stability, a ply which can be printed upon to provide for the package lebeling and other markings, and a ply which provides a gas or moisture barrier.
For some applications, it is the practice to construct the package or bag by heat sealing the laminated material to form a bag or receptacle. The package may then be filled, and its opening heat sealed closed to produce a unit ready for shipping. Packages or bags of the above description may be used in vacuum packing, a familiar technique in which the contents are exposed to a reduced atmosphere during the sealing operation to draw off air (which may contribute to spoilage) or to eliminate gases which might otherwise evolve or diffuse out of the product over time. The present invention may be used, however, to equal advantage, with vacuum, non-vacuum or gas-flushed packages.
The seals for packages of the above-described type must of course be strong enough to withstand routine handling and foreseeable mishandling, and to avoid spillage due to failure of the closure. Also, the closure must be strong enough and permanent enough to resist tampering. In typical prior art packages, the seals are often as strong as the other seams of the package. Opening may require the use of knives, scissors or other cutting instruments. As an alternative, schemes have been proposed for the use of frangible elements, tear strips or drawstrings, to facilitate opening. Each of these in some measure complicates the production process, and results in partial or complete destruction of the package upon opening. This latter attribute is itself undesirable, for in the marketing of certain products, it is common to open the package, process the contents (as, for example, in the grinding of coffee beans), and return the processed contents to the package.
The present invention provides a flexible package which features an easy opening peel seal which can be manufactured in a variety of strengths, and which, unlike known previously existing peel seals is sufficiently strong to meet all of the usual requirements, including the ability to reliably retain vacuum. Another aspect of the novel peel seal of the present package is extreme simplicity of manufacture, in which the making of the seal lends itself to continuous processes of the kinds used to make and fill packages. Yet another object and advantage of the present invention is its provision of a seal whose integrity may be inspected and verified virtually at a glance, because separated or failed parts of the seal take on a distinctive appearance.